Internet Sharing not working on desktop PC

[FreeBaGeL]

I have an HTC Touch Pro. When I plug it into my laptop via USB, I can use internet sharing to use the internet on my laptop no problem. The Touch Pro shows the status as connected, and I can browse the internet on my laptop.

However, when I plug it in via USB to my other computer, it doesn't work (Windows XP). The status on the phone still says "check usb cable connection" and I cannot connect to the internet on my computer. I know the USB ports on the computer work fine as I can use them on other devices, and also when I plug in the phone the computer recognizes it and asks if I want to use active sync or just use it as a disk drive, so it's definitely connected but the internet sharing isn't working.

Also, I've heard of ActiveSync causing a problem with it so I'm not using that, I'm choosing to connect as a disk drive and still no luck.

Help!